1. Field of the Invention
The present invention generally relates to railroad end-of-train (EOT) units, and more particularly to an improved system for supplying power for such EOT units.
2. Description of the Prior Art
End-of-train units coupled to the last car of a train are used extensively by railroads to monitor air pressure in the air brake pipe, which runs the length of the train, and other parameters such as motion, and transmit this information to a head-of-train (HOT) unit located usually in the locomotive. In addition, in some units the head-of-train (HOT) unit can transmit an emergency brake application command to the end-of-train unit. Typically, a radio transmission is used for communication between the HOT and the EOT. An EOT unit typically includes a transmitter, a microprocessor, and transducer input ports for brake pressure, motion and other inputs.
EOT units in operation today are powered by electric storage batteries; see for example U.S. Pat. No. 4,487,060. Nickel/cadmium (NICAD) and lead/acid batteries are both used; each has certain advantages and certain disadvantages. Batteries have to be recharged and/or changed sometimes in remote places. Thus, the railroad has to have batteries or battery chargers in locations throughout the railroad. Due to the severe environment (vibration and rough handling of equipment) the normal life of the rechargeable batteries used is significantly reduced.